Signaling system



R. M.l HOPKINS SIGNALING SYSTEM IN1/mma.

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y Patented Maa lalezs. Y.

UNlrrengs'rAres e, i, szane orifice;

RICHARD M. HOPKINS, OF 'RUTHERFORD, NEWT' 'I''B'BIEY,A ASSIGNOR TO AMERICAN DISTRICT TELEGBAPH COMPANY, F CITY, NEW JERSEY, A CORPOBA- TION OF NEWJEBSEY.

Application led July To Vzzllxlwhom t may concern.'l

Be it known that I, RICHARD M. HorKrNs, a citizen of the United States of America,

and resident of Rutherford, county of.

to systems for the protection of vaults and Y the like from burglary, and is designed to give a positive and reliable automatic indication at a central oiiice 'when any attempt is made to break into or enter any vault protected by it. By this system the ordinary expensive wire or foil linings covering the walls. ceilings, and floors of vaults are not required, and means is provided whereby sounds, inevitably made in attempts to break into or otherwise enter' the protected premises, cause the' sending of an alarm to the central station. A

ln a companion application, Serial No. 308,786 filed July 5, 1919, l have disclosed a detection system somewhat similar to that herein described, wherein a sound detector, located in or about the premises to be protected, is caused, when it operates, to operate a transmitting relay also located in proximity to the protected premises, by means of a coherer, constituting one form of breakdown resistance,.which normally cuts oli' operating. current from the relay, but under the influence of the static eect of current waves produced by the operation of the detector, coheres and so permits the passage of operating current to said relay; which relay, then operating, transmits a signal through a suitable circuit to a central station, and there operates alarm indicating means. In the present invention, the coherer and relay are themselves located at or about the central station, and the current waves produced by the operation of the detector are transmitted to them through a' suitable circuit. The present system has the advantage of greater simplicity, but is adapted for use mainly where t ere is no great liability of trouble arisingv from induction or from sneak currents; the system of my said companion application, however, though somewhat more complicated, is substantially free from disturbance vby induction or sneak currents.

SIGN ALIN G SYSTEM.

191e. serial No. 308,787.

My invention, therefore` comprises a detector connected by a suitable circuit to signal receiving, apparatus comprising a coherer or breakdown resistance and means controlled thereby for receivingr the alarm. .My invention further comprises the inductive connection of the detector circuit to the coherer circuit, and other features as hereafter described. u

The object of my invention is to provide a detection system of extreme simplicity and of great reliability under conditions for which it is suited. and the cost of maintenance of which is low.

The accompanying drawing illustrates, diagrammatically, a system embodying my .invent1on. l In the said drawing, 1 designates a detector, adapted to be located in or about the premises to be protected, and usually of the general nature lof a telephone transmitter of sens1t1ve type. and adapted to transmit to the central station, through a circuit 2,5

sounds occuring in or near the protected premises` for example, sounds such as will inevitably be made in attempts to break into a vault within which the detector is located, or sounds made by tools used within the vault.

3 designates an electro-responsive instrument such as a relay, preferably of somewhat sensitive type, located at or near the central or alarm-receiving station; l a coherer, and 5 a circuit containing the magnet circuit of relay 3, and also the coherer, together with a source of current supply 6. The connection between circuits 2 and 5 is preferably inductive, through a transformer lil) I1-8, and preferably this transformer is of a set-up` type. as thereby current waves in circuit 5 may be produced readily which are sufliciently static in character to cause prompt operation of the coherer.

As will be understood readily when the coherer is in its normal decohered condition, it prevents the passage of current from the source 6 through the magnet coil of relay 3; but in the event that sounds shall cause operation of detector 1, the resulting current waves in circuit 2, inductively transmitted to' circuit 5 as waves of sucient potential to cause cohering inthe coherer, make that coherer conductive to the current from source 6, and so cause relay 3 able alarm indicating means may be used.

After an alarm has been received, and the cause remedied, the coherer must be decohered to return the ap aratus to normal condition. A tap given with a linger usually suiiices for this.

If, as is frequently the case, the coherer is located in a place, such as a telegraph office, where occasional sparking of other instruments results in the production of wireless waves tending to cause the coherer to cohere, this tendency may be decreased by connecting circuit 5 to ground through a condenser 15, each side of the coherer being thus rounded and the alarm receiving circuit eing located entirely at the central station, can be made so short that it will not be lcapable of storing suiiicie'nt static energy to affect the coherer. In addition, I find it desirable to use a coherer only partly filled with the metallic particles which arev designed to form a conductive path by cohermg; in other words, with advantage the coherer used may be one illed to a considerably Iless extent than is customary in the case of coherers intended for wireless work. Y f

The circuit 2 is constantly under'test, for a short circuit or break in said circuit will cause a momentary disturbance in such circuit suicient to cause cohering of the coherer. 1

Other examples of breakdown resistance devices which may be employed in lieu of the coherer are, a, boron resistance, such as is commonly termed a boron shunt, which may be substituted for the coherer, and a selenium cell, which also' may be substituted for the coherer, a reflecting alvanometer in circuit 2 being arranged to reflect a beam ,of light variably on and off the selenium cell, under the influence of the current waves in circuit 2, produced by the action of the detector.

Features possessed in common by the present invention and by that of the `said companion application are claimed in said companion application.

' l What I claim is An alarm system comprising in combination an alarm-receiving circuit at a central station embodying an'electro-responsive instrument, a source of vcurrent supply and a coherer; means including a detector of the microphonic type located at a distant point, circuit means` connecting the detector with said receiving circuit, and means for ground- `ing both sides of the coherer through a condenser.- v A `In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

RICHARD M. HOPKINS. Witnesses:

A. E. S'rnAnNs, E. N. RABAN. 

